Effect of macromolecule hydrophobicity on liquid-liquid equilibrium of aqueous two-phase system composed of (NH4)2S2O3

Aqueous two-phase system (ATPS) is an efficient technique used in the extraction and purification of metals, biomolecules, enzymes, natural dyes, and microorganisms1. This system is recognized for being environmentally friendly because its components are nontoxic, biodegradable, and inexpensive1a. In addition, ATPS spends less time to phase splitting in contrast with conventional solvent extraction. In the present work, the phase diagrams for macromolecules (PEG1500, PPG400, pluronic10R5 or L35) + (NH4)2S2O3 + H2O were experimentally determined at 298.2 K. Fig.1 shows the phase diagrams for the L35, pluronic10R5 or PEG1500 + (NH4)2S2O3 + H2O. The copolymers L35 and pluronic10R5 have segments of polypropylene oxide (PO) in your structure, while the PEG1500 shows only segments of ethylene oxide (EO). The copolymers are more hydrophobic than PEG1500, so the biphasic region is higher. However, the biphasic region of the ATPS with pluronic10R5 and L35 is similar. Fig. 2 shows the phase diagrams for the PPG400 and PEG1500 + (NH4)2S2O3 + H2O at 298.2 K. The phase separation process occurs at lower concentrations of polymer and electrolyte for ATPS formed by PPG than observed in the ATPS formed by PEG. This occurring because PPG is more hydrophobic than PEG, the PPG structure decreases the water-macromolecule and electrolyte-macromolecule interactions, favoring the phase separation process at lower ATPS component concentrations2.